Dec 20, 2012 3:39 PM

I have worked in the quarry industry for many years over this time I have accumulated these balls which are actually embedded in the rock I split. Seem to find them in the bottom rock layer which is approximately100-150ft down. Can anybody tell me more information about these as I am bamboozled?thanks.... Also shown full size football to show size.

They are probaby concretions. I can see from one of the larger specimens that the bedding (assuming the rock is sedimentary) goes through the ball (or vice versa). That supports the concretion hypothesis. Concretions are a bit like crystals in that they grow out from a nucleus and represent a difference in chemistry. With concretions, it is often the matrix between the particles that is altered - becoming harder. As a result, the concretion may separate from the softer rock surrounding it. Concretions are not always as regular as yours - a lot depends on anisotropy in the permeability and other properties of the rock. I'm sure if you do a bit of Googling, you'll find out way more than you needed to know about concretions!

Thanks for your reply . Looked on the internet could not find many from UK are these rare or ten a penny. This picture was taken a while ago and have afew more larger balls now and one which is completely flat on both ends. Do you think the museum would be interested in these to display. Thanks again.....

You are quite correct in that these balls look like pothole balls, but they are ruled out by the situation (weathering out of the solid rock rather than being found in modern or fossil potholes).

chris:

1. They are not that rare, just not so often commented-upon.

2. Regarding displaying them at the NHM: I can't speak for the NHM, but by all means email them, including a link to this thread. But first, having asked the question in open forum, wait and see if you get an answer from one of the NHM NaturePlus staff. (If you check my profile, you'll see I am not affiliated with the NHM; but you weren't really to know that.)

Another idea would be to possible send one of the smaller examples to the museum along with some pictures of them in situ that way you could have some of the experts there have a look and get their feedback on whether they would be interested in displaying them. Make sure you let us know if you find out anything!